Thanks 
To add a new kingdom, you have to add a mixinto for stonehearth/data/playable_kingdom_index.json.
An example of this can be seen on the Bastioneers mod: [Mod] (A20) The Bastioneers! More Dangerous (and Mod-Friendly) Than Ever! Help me test for A20!
Then, reference your own population file, based on any of the existing ones.